I might be overthinking it but....

[McCabe-Thiele (Ted)]

After reading a few posts on using cold galvanising spray for the inside of mudguards I'm thinking that's a good idea except most primers I believe are porous so water molecules could pass through the interstitial molecular spaces thus trap water causing rusting.

Imho it needs an additional step with silver paint or clear lacquer to prevent the moisture getting through.

[Orcade-Ian]

Ted,
I did the brake calipers on our MX-5, using Bilt Hamber Deox-C to get rid of every trace of rust and then sprayed them with Electrox (90 odd % zinc rich paint) from the same company.  That was 3 years ago and they still look as good as when I did them.  OK, we don't use that car in the winter but we ARE in Orkney only a mile or so from the Atlantic!  You wouldn't need to do the first stage and could paint over them if needed.  It's the rolled edges and spot welded/riveted brackets that are the worst bits on mudguards as you well know.

Ian

[Oddjob]

Use zinc182 paint Ted not the spray. If you look at the mudguard I sent you you can see all the voids are filled, even the inner part of the wire tunnel is done, I blocked the bottom of the tunnel and filled it with paint and then drained it out. You can also just fill all the rolled edge voids by putting more on the brush, which you can't really do with spray.

I've been doing this since the 70s and when I sold a rear mudguard that I had done 30 years before it was still mint under the paint, even if the paint gets scratched it still protects near it.

Places I commonly do it are inside the headlight rim, inside the fork ears and down the fork tube on them, inside the points cover, inside the handlebars, front mudguard when I was using a metal one, inside the wheel rims, back of the exhausts to name those I an just think of.

[McCabe-Thiele (Ted)]

So are you all saying that the primer is not pourous?

[Oddjob]

Doesn't seem to matter if it is Ted, I think it's more critical for all the recesses to be filled so they don't harbour water and rust it silently until it bursts through the other side. Do your new bars, just block the holes, thin the paint ever so slightly, fill the bars completely and then drain out. Check in 10 years and you'll see they are still rust free.

[McCabe-Thiele (Ted)]

Great idea Ken but 10 years is probably double the amount of sand in the hourglass of my life. The next owner/caretaker can do that as and when. Not being morbid here just a pragmatic realist. I'm 75 this year if I make 80 that would be double the life expectancy I was given in 2018 before loosing a kidney was on the agenda.
Gawd that does read as though I am pathetic/full of self pitty - far from It's just reality at my age.

Like many people I know personally as well as friends here who have lost wives /husbands/friends my outlook has changed over the last few years. I share this post knowing that life is not a dress rehearsal but finite.
But be buggered if I will drop off the perch before I finish this build.lol😀😀😀

[Oddjob]

You never know what life will come up with Ted, could be tomorrow, could be 20 years from now. I'm thinking another 30 years will do me, after that I may start getting bored 

[McCabe-Thiele (Ted)]

You have jogged my memory Ken about extending the longevity of stuff.
I've only ever bought one new car in my life it was a Vauxhall Astra Mk1 1600 SR. After collecting the vehicle from the dealer in Ilkeston  it went straight into the garage at home where I full under sealed all four wheel arches with a brush using turps based underseal. I then waxoyled all the insides of the sills chassis rails etc.final coat of waxoyl on top of the wheel arches over the underseal. Did inside the  doors a tailgate.
Sold the car after 4 years as the crank mains were rumbling - the dealer told me that there had been a batch of poor cranks. Sold the vehicle so never reaped any benefit from my efforts.

On my 1960s Mini that had new sills and a boot floor replaced I covered all the welds with glass fibre gell and tissue paper glass fibre to keep the water out followed by body Schultz and yes waxoyl.  Were not that different are we Ken!

[Oddjob]

I did the same with a Vauxhall Astra Mk4 2002 model Ted, took off all the door skins from new, waxoyl inside the doors and in the sills where possible. Sold the car last year after it had been sat on my drive for 13 years and never moved. It was quite modified and he wanted to keep it for when he passed his test, eventually he just bought a sport car and said he didn't want it anymore, made me mad as I could have sold it in 2009 when I took it off the road for a good amount due to all the mods on it.

13 years of standing and the doors and sills were immaculate, no rust at all. Sold it to a scrap dealer in the end who said it was far too good to scrap and put it back on the road, he sold it for £2500 after spending around £1000 on fixing the problems it had.

Parts are getting harder to source Ted, and a lot more expensive when you can, seems to me that we must all try and make the present parts last as long as possible, my 500 will get passed down in the family so it will outlast me and probably whoever inherits it.

[McCabe-Thiele (Ted)]

Unfortunately on my side of the family none are bikers. My BiL is but let's not go there unless he wanted to buy it. It's an inter sibling thing.